Fluid particle monitor and methods related thereto

ABSTRACT

A fluid analysis system and method for in situ optically imaging a fluid, such as lubricating oil, sampled from a flow path. The system has a chamber with an inlet in fluid communication with fluid flowing under pressure in the flow path. The pressure of the received fluid in the chamber is reduced, the reduced pressure fluid is directed from the the chamber into the fluid analysis system, and the fluid analysis system optically images the fluid. The fluid analysis system can produce data representative of particle size, particle shape, or number of particles. In one embodiment, a valve for directing fluid to the chamber and a valve for returning fluid from the chamber to the flow path under pressure allow the fluid to flow through the chamber for a period before shutting the valves, reducing the pressure of the fluid, and optically imaging the fluid.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of, and claims priority from, Application No. 20026178, filed in Norway on Dec. 20, 2003, the disclosure of which is incorporated herein in its entirety.

FIELD OF THE INVENTION

[0002] This application relates to a fluid analysis apparatus and a method for sampling and monitoring of a fluid flowing in a flow path, and more particularly, for optically monitoring the particles present in a fluid.

BACKGROUND

[0003] Determination of the quantity, size, characteristics, and types of particulate matter in fluids is important for many applications such as monitoring fluids in engines and rotating machinery, industrial quality control, food processing, medical analysis, and environmental control. For example, as an engine ages, it flakes metal particulates into its lubricating oil. The size, number, and shape of particulates correspond to engine condition, and can alert one to imminent engine failure. Predicting failure is critically important in aircraft engines, where sudden failure could result in a crash and loss of life.

[0004] In the early stages of wear engines shed smaller particulates, on the order of 50 microns or less. These particulates have characteristic shapes indicative of the type, source, and nature of the wear. As the wear process progresses, the amount and size of particles increase. Sensing and identifying smaller particles allows early identification of faults, more time for corrective maintenance action, and fewer unexpected catastrophic failures. Current methods to accomplish this can be costly, time consuming, use only a small sample of oil, and/or are not thorough in fault identification.

[0005] In earlier systems, oil particulates were checked by extracting an oil sample, and sending the oil to a laboratory for testing. A system for sampling a fluid from a pressurized fluid system is disclosed in U.S. Pat. No. 5,370,005 to Fjerdingstad, the disclosure of which is incorporated herein in its entirety.

[0006] U.S. Pat. No. 5,572,320 to Reintjes et al. and U.S. Pat. No. 6,049,381 to Reintjes et al. disclose optical imaging systems for monitoring suspended particles by pumping the fluid through passageway between a detector and a light source and forming an image of the particles. U.S. Pat. No. 6,104,483 to Sebok et al. discloses an optical flow cell suitable for a fluid inspection system. U.S. patent application Ser. No. 09/923,973 to Sebok et al. discloses a fixture for imaging particles passing through a cell. U.S. patent application Ser. No. 10/143,638 to Miller et al. discloses a temperature compensating optical debris analysis fixture. U.S. patent application Ser. No. 10/336,143 to Niuewenhuis et at. discloses an apparatus for determining the size and/or shape of small particles. The entire contents of each of these documents is incorporated herein in its entirety.

SUMMARY

[0007] One embodiment of the invention is a method for in situ sampling and monitoring of a fluid flowing in a fluid path. The method includes opening a first valve connecting the flow path to a chamber to direct the fluid from the fluid path into the flow chamber, opening a second valve disposed downstream of the first valve, the second valve arranged to allow the fluid to exit from the chamber into the flow path at a location downstream of the first valve, and allowing the fluid to circulate through the chamber for a period. Thereafter, a portion of the fluid is trapped in the chamber by closing the first valve and the second valve, the pressure of the fluid in the chamber is reduced, the fluid in the chamber is directed to flow through a fluid monitoring device, and the fluid flowing through the fluid monitoring device is analyzed to produce data representative of at least one fluid characteristic.

[0008] Another embodiment of the invention presents an apparatus for in situ sampling and monitoring a fluid flowing in a flow path. The apparatus includes a chamber with an inlet and an outlet, the chamber being adapted for receiving fluid from the flow path. A first valve is arranged for connecting the inlet to the flow path, a second valve is arranged for connecting the outlet to the flow path, and an access valve leads fluid from the chamber into a fluid monitoring device. A pressure reducer is connected to the chamber and adapted to reduce pressure of the fluid in the chamber to a pressure suitable for the fluid monitoring system.

[0009] In another embodiment, a fluid monitoring system for optically imaging fluid sampled from a flow path includes a chamber in fluid communication with fluid flowing under pressure in a flow path, the chamber having an inlet for receiving at least a portion of the fluid from the flow path, means for reducing a pressure of the received fluid in the chamber to a reduced pressure, an optical imaging device in fluid communication with the fluid in the chamber, and means for directing fluid from the chamber at the reduced pressure to the optical imaging device for imaging fluid received from the chamber.

[0010] In another exemplary embodiment, a method for sampling and optically imaging a fluid flowing in a flow path includes directing at least a portion of the fluid flowing in the flow path into a storage chamber, reducing the pressure of the fluid in the storage chamber, directing at least a portion of the fluid from the storage chamber into a fluid analyzer, and optically imaging the fluid directed from the storage chamber.

[0011] Other features and objects of the invention will become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0012] For a complete understanding of the objects, techniques, and structure of the invention, reference should be made to the following detailed description and the accompanying drawings.

[0013]FIG. 1 is a schematic view of a fluid analysis system according to an embodiment of the invention.

[0014]FIG. 2 is a schematic view of a fluid analysis system according to an embodiment of the invention which includes a remote data transfer from a test station to a remote site.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0015] The apparatus illustrated in FIG. 1 is a fluid analysis and sampling system which includes a fluid sampler 1 and fluid monitor 2 suitable for automatic, semi-automatic, or manual on-line monitoring of fluid in a system. An advantage of the fluid analysis system of FIG. 1 compared to previous systems is that fluid can be monitored while the system to be monitored is in operation, without the need to transport a discrete sample of fluid from the engine to a separate fluid monitoring system. This reduces the expense and delays associated with previous monitoring systems.

[0016] The following discussion of preferred embodiments describes monitoring the lubricating oil in an engine, however, the apparatus and methods are equally applicable to other types of fluid from various fluid sources. As one example, the apparatus and method described herein is suitable for monitoring hydraulic fluid for particles including debris and contaminants such as water. Systems suitable for this type of monitoring include but are not limited to engines and hydraulic systems of ships and aircraft, and stationary turbomachinery such as found in power generation plants. The fluid analysis system can receive and monitor fluid from engines or other fluid sources while the engine or machinery is operational, thus reducing down-time. While is it preferred that the fluid be monitored while the engine or machine to be monitored is operational to receive a representative sample of fluid, it is also possible to use the fluid analysis system while the engine or machine is cold and not running.

[0017] The fluid sampler 1 is arranged to receive a portion of the fluid in the engine for sampling and monitoring through a line 3 which defines a flow path from the engine or other fluid source to the fluid monitoring system. A chamber 6 has an inlet 4 for receiving at least a portion of the fluid from the line 3. In one embodiment, valves 7 and 8 are arranged in the line 3 to allow fluid to flow from the line 3 through the inlet 4 and to return the fluid to the engine. The line 3 is any type of suitable conduit for transporting fluid at an operational pressure to the chamber 6, and includes a bypass line 5 and a downstream portion 14 which is downstream of the chamber outlet 21. The chamber outlet 21 can be controlled by a valve 8 in the line 3 for returning fluid from the chamber 6 back into the line 3. Although it is preferred that the outlet 21 of the chamber 6 be arranged to direct fluid to a location in the line 3 downstream of the inlet 4, the system can also be arranged to return the fluid to the line at a point upstream of the inlet 4 and valve 7 if desired. Alternatively, the fluid flowing from the chamber 6 can be discarded outside of the system or can be reduced in pressure and introduced into a low pressure point in the fluid cycle, such as at the engine sump or other fluid reservoir. The valves 7 and 8 can be arranged to allow only a portion of the fluid flowing through the line 3 to flow into the chamber 6 (so the flows are “in parallel”), however, it is preferable that the valves allow all of the fluid flowing in the line 3 to flow into the chamber 6 (so the flows are “in series”).

[0018] In one embodiment, the valves 7 and 8 are normally positioned so the entire flow with its full complement of debris particles flows through bypass line 5 and no fluid enters the chamber. To fill the chamber 6, the valves 7 and 8 can then be opened to divert all of the flow into the chamber 6 through the inlet 4. The fluid flows through the inlet 4, into the chamber 6, and through the outlet 21, filling the chamber 6. The valves 7 and 8 can then be closed to trap a quantity of fluid trapped in chamber 6.

[0019] Opening the downstream valve 8 before the upstream valve 7 is opened may reduce the likelihood that debris will accumulate in the chamber, although the valves can also be closed simultaneously, or the upstream valve can be closed first. In addition, opening the downstream valve 8 before the upstream valve 7 is opened is also recommended, although any sequence can suitably be used.

[0020] In operation, it is recommended that the valves 7 and 8 remain open for a period of time to allow any debris which has accumulated in the fluid sampler or in the fittings and valves to be flushed out of the fluid sampler and to allow the fluid in the chamber 6 to be representative of the fluid in the overall system. The recommended period is at least about three to five minutes, and preferably at least 15 minutes. Other periods may also be suitable for individual systems, and can be determined through testing and experience.

[0021] To reduce the pressure of the fluid in the chamber 6 before it is directed to the fluid monitor 2, the fluid analysis system also includes means for reducing the pressure in the chamber. In the embodiment illustrated in FIG. 1, the pressure reducing means includes an expansion chamber 10 in fluid communication with the chamber 6. The expansion chamber can be connected to the chamber 6 by a suitable valve 9, which is preferably opened after the valves 7 and 8 have been closed and fluid is trapped in the chamber 6. Opening the valve 9 allows a portion of the fluid in the chamber 6 to flow into the expansion chamber 10, thereby relieving the pressure in the chamber 6. The system in FIG. 1 can also include a pressure relief valve 12 that opens to allow air to enter chamber 6 as the fluid is withdrawn from chamber 6 through the monitor system in order to maintain the pressure in chamber 6 at about the pressure of the environment outside of the chamber 6, e.g., at about one atmosphere. The expansion chamber 10 can take the shape of an increased width segment of the pipe 23, as illustrated in FIG. 1. Alternatively, the expansion chamber can be a length of pipe 23 without an added width segment, or any other suitable shape. The expansion chamber 10 can be rigid or flexible, and can be of fixed size, or can be expandable so the volume increases to receive flow from the chamber 6. Other devices for relieving the pressure in the chamber 6 will also be apparent to the skilled reader, including, but not limited to, bleed valves for draining fluid from the chamber 6 until the pressure is reduced.

[0022] Once the valves 7 and 8 have been closed to trap fluid in the chamber 6, and the pressure in the chamber 6 has been reduced, the fluid in the chamber 6 can be directed to the fluid monitor 2 through a conduit 22. The conduit 22 can be a line, pipe, tube, or any other suitable structure for directing fluid from the chamber 6 at the reduced pressure to the fluid monitor 2. A valve 11 can be arranged in the conduit 22 or at the chamber outlet to control the flow of fluid to the fluid monitor 2, e.g., to prevent the flow of fluid from the chamber 6 until the pressure is reduced, and to allow the fluid to flow into the fluid monitor 2 when desired. In an exemplary embodiment, transparent, flexible, polymeric tubing can be connected to an outlet of the valve 11 and an inlet of the fluid monitor 2.

[0023] Although FIG. 1 illustrates an embodiment having both an expansion chamber 10 and a separate exit conduit 22, other embodiments can include an exit conduit 22 with an integral pressure reduction device, e.g., a bleed valve, expandable piping, expansion chamber.

[0024] The fluid analysis system can also include a pump for pumping fluid from the conduit through the fluid monitor 2. The pump (not shown) can be either integral to the fluid monitor 2, as in the FIG. 1 embodiment, or can be arranged external to the fluid monitor 2. The pump can be of any suitable type, and in one embodiment, is a peristaltic pump which contributes little or no contamination to the system.

[0025] The fluid monitor 2 can include the optical imaging system described in U.S. Pat. No. 5,572,320, a version of which is available commercially under the tradename Lasernet Fines from Lockheed Martin Corporation, or can be any other type of suitable fluid monitoring device. The monitoring system 2 a analyzes and classifies the particles in the fluid received from the chamber 6 a, and produces quantitative measurements of the debris characteristics based on size and shape distributions of the debris, suitable for evaluating the condition of the machine. The monitoring system 2 a thus produces data representative of the number, size, and shape of particles in the fluid. The fixtures described in U.S. Pat. No. 6,104,483 to Sebok et al., U.S. patent application Ser. No. 09/923,973 to Sebok et al., and U.S. patent application Ser. No. 10/143,638 to Miller et al. can also be included in the fluid monitor 2.

[0026] The structures and connections which are subjected to the pressure of the fluid in the line 3 should be able withstand the pressure without rupture or leakage. The flow conduit 24 downstream of the valve 11, the fluid monitor 2, and the flow conduit 25 from the flow monitor 2 to the low pressure engine sump do not need to withstand the high pressure of the fluid in the line 3.

[0027] An advantage of the system illustrated in FIG. 1 is that the system can be configured as a closed system, so the fluid that flows through the chamber and/or fluid monitor is returned to the engine. Fluid that has passed through the fluid monitor 2 can be returned through the flow path 13 to a low pressure section of the engine. As illustrated in FIG. 2, low pressure fluid is returned from the fluid monitor 2 a to the engine sump 30. Thus, when the fluid analysis system shown in FIG. 1 is configured as a closed system, there is no need for operators to dispose of the fluid samples or to replenish the overall fluid reservoir.

[0028] Another advantage of the system illustrated in FIG. 1 is that no sample jar is necessary to collect a sample in the chamber 6. Nor is it necessary to manually open the chamber 6, retrieve a sample, and transport it to a separate fluid monitor. A further advantage that the fluid analysis system is a real-time monitoring system which can be used on a periodic basis, with the results being communicated to a user only when the number, shape, or size of particles indicates that an engine wear threshold has been reached. If such a threshold is reached, the sampling and fluid analysis can rapidly be repeated without the need to manually retrieve another sample jar of fluid.

[0029] The valves in the fluid sampling system can be implemented as manually or electrically controlled valves. In one embodiment, the inlet and outlet valves 7 and 8 arranged for manual operation, and valves 9 and 11 are implemented as electrically controlled and operated valves, whose sequence is controlled by suitable programming to allow semi-automatic operation. In another embodiment, each of valves 7, 8, 9, and 11 are electrically controlled and operated valves, with the valve sequence being controlled by suitable programming to allow automatic operation, operation at a predetermined schedule, or operation on demand by a local or remote operator. The data from the fluid monitor can be stored locally on suitable information media, for example, in computer associated with the monitor system 2. In addition, the rough or analyzed data can be transferred to a remote site for evaluation or maintenance support as determined by suitable computer commands by electronic, optical data transfer, or with a modem, or any other suitable data transfer method. Transfer of data can be automatically done after each analysis record, after an accumulation of a number of analysis records, on a timed sequence, or on demand by a local or remote operator.

[0030] In an alternative method of operation of the fluid analysis system of FIG. 1, the valves 7 and 8 are normally positioned to direct all of the fluid flowing in the line 3 into the inlet 4, through the chamber 6, and to return the fluid from the chamber 6 through the outlet 21 and into the downstream flow path 14. Thus, in normal operation, little or no fluid flows through the bypass line 5. In order to direct the fluid to the fluid monitor 2, valves 7 and 8 are positioned so no further fluid flows through the chamber 6 and all the fluid flows through the bypass line 5. The fluid present in the chamber 6 is then reduced in pressure and directed to the fluid monitor 2 for analysis in the manner discussed above. After the fluid monitoring operation is complete, the valves 7 and 8 can be repositioned to direct the fluid from the line 3 through the chamber 6 and return it to the flow path 14. This sequence has the advantage that the fluid flowing through the chamber can be sampled at any desired time, without the need to delay fluid monitoring to wait the recommended period to allow the fluid flow through the chamber 6 to flush out excess debris or particles that may have accumulated.

[0031]FIG. 2 illustrates an embodiment in which the fluid sampler 1 and fluid monitor 2 are arranged in a fluid analysis system having a computer with remote data transfer via a modem to a receiver 34 at a remote site. The receiver can be configured to receive data from many fluid analysis systems, so a user can evaluate the condition of many different engines or systems without traveling to each site individually.

[0032] In the embodiment shown in FIG. 2, the fluid monitor 2 a is an optical imaging system available commercially under the tradename Lasernet Fines-C, or “LNF-C”, and the fluid sampler includes a modified chamber 6 a from the fluid sampling system available under the tradename DYNASAMP, available from FRAS AS, Hovik, Norway system and related to U.S. Pat. No. 5,370,005. The chamber 6 a is modified to include a port for an expansion chamber, an exit port for an exit conduit, and without a sample jar. The monitoring system 2 a analyzes and classifies the particles in the fluid received from the chamber 6 a, and produces quantitative measurements of the debris characteristics based on size and shape distributions of the debris, suitable for evaluating the condition of the machine.

[0033] The embodiments described herein can provide significant advantages over other debris monitoring systems by providing real-time analysis of particle characteristics, and can provide remote monitoring of multiple systems with high accuracy and low cost.

[0034] The invention has been described with reference to certain preferred embodiments thereof. It will be understood, however, that modification and variations are possible within the scope of the appended claims. 

1. A method for sampling and monitoring of a fluid flowing in a fluid path, the method comprising: opening a first valve connecting the fluid path to a chamber to direct the fluid from the fluid path into the flow chamber, opening a second valve disposed downstream of the first valve, the second valve arranged to allow the fluid to exit from the chamber into the flow path at a location downstream of the first valve, allowing the fluid to circulate through the chamber for a period, trapping a portion of the fluid in the chamber by closing a first valve and a second valve, reducing the pressure of the fluid in the chamber, directing the fluid in the chamber to flow through a fluid monitoring device, and analyzing the fluid flowing through the fluid monitoring device to produce data representative of at least one fluid characteristic.
 2. The method according to claim 1, wherein the period is sufficient to provide a representative sample of the fluid in the flow path.
 3. The method according to claim 1, wherein the period is at least 3 minutes.
 4. The method according to claim 1, wherein the period is at least 15 minutes.
 5. The method according to claim 1, further comprising: releasing the fluid from the monitoring device.
 6. The method according to claim 1, wherein the reducing the pressure of the fluid in the chamber comprises allowing at least a portion of the fluid in the chamber to flow into an expansion chamber.
 7. A method according to claim 1, wherein the reducing the pressure of the fluid in the chamber comprises opening a valve in fluid communication with the chamber and an expansion chamber.
 8. A method according to claim 1, wherein the fluid monitoring device is an optical device comprising a light source and an optical detector.
 9. A method according to claim 1, comprising pumping at least a portion of the fluid in the chamber to the fluid monitoring device.
 10. A method according to claim 9, wherein the fluid monitoring device comprises a pump for pumping the fluid to the fluid monitoring device.
 11. A method according to claim 1, wherein the at least one fluid characteristic is particle size, particle shape, or number of particles.
 12. An apparatus for in situ sampling and monitoring a fluid flowing in a flow path comprising: an inlet and an outlet connected to a chamber, the chamber being adapted for receiving fluid from the flow path through the inlet and returning the fluid to the flow path through the outlet, a first valve for connecting the inlet to the flow path, a second valve for connecting the outlet to the flow path, an access valve provided for leading fluid from the chamber into a fluid monitoring system, a pressure reducer connected to the chamber and adapted to reduce pressure of the fluid in the chamber to a pressure suitable for the fluid monitoring system.
 13. An apparatus according to claim 12, further comprising: the fluid monitoring system.
 14. An apparatus according to claim 13, wherein the fluid monitoring system is an optical system comprising a light source and an optical detector.
 15. An apparatus according to claim 14, wherein the fluid monitoring system optically images particles in the fluid to produce data characteristic of at least one of particle size, particle shape, and number of particles.
 16. An apparatus according to claim 15, further comprising: a computer in communication with the fluid monitoring system adapted to store the data or transfer the data from the monitor system.
 17. An apparatus according to claim 12, further comprising: an expansion chamber in fluid communication with the third valve for reducing pressure of the fluid in the chamber.
 18. A fluid analysis system for monitoring particles in a fluid, the system comprising: a chamber in fluid communication with fluid flowing under pressure in a flow path, the chamber having an inlet for receiving at least a portion of the fluid from the flow path, means for reducing a pressure of the received fluid in the chamber to a reduced pressure, an optical imaging device comprising an optical source and an optical detector arranged to image particles present in fluid flowing through the optical imaging device, and means for directing fluid from the chamber at the reduced pressure to the optical imaging device for imaging.
 19. A fluid analysis system according to claim 18, wherein the system is an engine fluid analysis system.
 20. A fluid analysis system according to claim 18, wherein the fluid is a lubricating oil.
 21. A fluid analysis system according to claim 18, wherein the fluid is hydraulic fluid.
 22. A fluid analysis system according to claim 18, wherein the means for reducing a pressure of the received fluid in the chamber to a reduced pressure includes an expansion chamber in fluid communication with the chamber.
 23. A fluid analysis system according to claim 22, comprising a third valve arranged to allow fluid in the chamber to flow into the expansion chamber.
 24. A fluid analysis system according to claim 18, wherein the means for directing fluid from the chamber includes a pipe or line connected between the chamber and the optical imaging device.
 25. A fluid analysis system according to claim 18, wherein the means for directing fluid from the chamber includes a pump for pumping fluid through the optical imaging device.
 26. A method for sampling and optically imaging a fluid flowing in a flow path, the method comprising: directing at least a portion of the fluid flowing in the flow path into a storage chamber, reducing the pressure of the fluid in the storage chamber, directing at least a portion of the fluid from the storage chamber into a fluid analyzer, and the fluid analyzer optically imaging the fluid directed from the storage chamber.
 27. A method according to claim 26, further comprising: returning the imaged fluid from the fluid analyzer to the flow path.
 28. A method according to claim 27, further comprising: returning fluid from the storage chamber into the flow path before directing at least a portion of the fluid from the storage chamber into the fluid analyzer. 